Anatomical study of Racosperma (ex-Acacia) mangium tissues cultured in vitro

In order to achieve adventitious shoot regeneration from young tissues of R acosperma mangium, several combinations of growth regulators were tested. K inetin (KIN) and alpha-naphthalenacetic acid (NAA) thidiazuron (TDZ) and NA A or indole-3-butyric acid (IBA), 4-CPPU and 2,4-dichlorophenoxyacetic acid (2,4-D) were added to basic medium composed of MS salts, MS vitamins and 3 % sucrose. Sections of hypocotyls and cotyledons of young seedlings were cu ltivated on these media. Calli developed on different media and, after two to three months, some of them regenerated organized structures. Histologica l studies revealed hypertrophy and hyperplasy of medular and cortical paren chyma cells of hypocotyl and cotyledon parenchyma. Formation of meristemati c cells and traqueary elements from parenchyma was observed during in vitro culture. In some cases, nodules of traqueary elements were formed. The hig hest differentiation into meristematic cells was found in cotyledon tissues cultured on 4-CPPU (8.07 mu M) and 2,4-D (1.13 mu M).